NEW YORK (AP) -- Smoke billowed out of the Washington Nationals' clubhouse when the doors opened after yet another victory celebration in New York. The NL East leader's fog machine recently has been getting plenty of use.

No special effects were needed on the field, though.

Stephen Strasburg bounced back from one of his worst starts to pitch seven efficient innings, Bryce Harper and Adam LaRoche each hit a two-run homer, and the Nationals beat the New York Mets 4-1 Thursday night to set a franchise record with their 11th consecutive win on the road against one team.

"We played really well here," manager Matt Williams said. "Now we've got to go do it at home."

The Mets' 11 straight losses to Washington in Queens are their most against one club at home. New York dropped 10 in a row to the Braves at Shea Stadium from 1991-92.

Strasburg (9-10) gave up three hits and an unearned run, improving to 2-8 in 13 road starts this season. He struck out eight and walked two.

Rafael Soriano was perfect in the ninth for his second straight save in the series and 28th overall. Washington finished a three-game sweep and increased its NL East lead to six games over Atlanta.

LaRoche and Harper both connected after walks by Dillon Gee (4-5). LaRoche homered in the first and Harper hit a long drive to right-center in the fourth.

"It felt great," said Harper, who missed time with a thumb injury. "That's one of the best balls I've hit all year."

The Nationals hit seven homers in the series, outscoring the Mets 14-4 and continuing a lopsided trend during a streak in New York that began June 30 last year. Washington has outscored the Mets 74-21 during the run at Citi Field, which now tops the Montreal Expos' 10 road wins in a row against the Chicago Cubs from 1982-83.

The Nationals are 25-4 at the Mets' home since Sept. 12, 2011. The teams play four more times this year in New York and three more in Washington, where the Nationals have won four of six meetings. They lead the season series 10-2.

"They've been a thorn in our side for the last two or three years for sure," Mets manager Terry Collins said.

Strasburg was coming off an outing in which he allowed a career-high four homers and seven runs to Atlanta, but he was rarely in trouble Thursday, working his fastball to both sides of the plate.

"I think I wanted to go out there and focus on the execution aspect and just pitch," Strasburg said, "make it a little harder for them to be comfortable."

After a throwing error by shortstop Ian Desmond in the fourth, Lucas Duda hit a sacrifice fly that was caught just in front of the right-center wall.

Nationals: RF Jayson Werth missed his third straight game but said he felt 50 percent better after getting a cortisone injection for his ailing right shoulder. Williams thinks Werth might be available to pinch-hit Friday against Pittsburgh and could even start Saturday.

Mets: RHP Matt Harvey (Tommy John surgery) heard from his manager a day after the ace boasted on a radio program that he was throwing in the mid-90s (mph) during a rehabilitation session. The team is being especially cautious with Harvey since starter Jeremy Hefner had a recent setback in his recovery from similar elbow reconstruction. But Harvey still says he wants to pitch this season. "The process is, right now you've got to understand it's the big picture, and the big picture is 2015. So back off," Collins said he told Harvey.

Nationals: RHP Tanner Roark (11-7) faces the Pittsburgh Pirates for the first time. In his first year in the rotation, the 23-year-old has allowed one run or fewer in 13 of his 20 starts since April 21.

Mets: RHP Zack Wheeler (7-8) faces the Cubs on Friday night. Wheeler pitched 6 2-3 innings of two-hit ball in his only start against Chicago on June 3, a game the Mets lost 2-1.

David Wright singled in the first to extend his hitting streak to 13 games. Only one of the hits during the run was for extra bases, a double off Washington's Craig Stammen last week.

Harper also homered in the series opener, giving him two long balls in a series since April 25-28, 2013, against the Reds, STATS said.